Sensitivity analysis for the aerosol retrieval over land for MERIS

The inversion of aerosol characteristics over DDV (Dark Dense Vegetation) targets is an intermediate and important step whenever atmospheric correction over land for the Envisat/MERIS instrument is performed. We present here the results of an error budget for every step of this inversion. We show that the crucial step is DDV selection based on a threshold on the ARVI (Atmospherically Resistant Vegetation Index). The cornerstone of this inversion is aerosol climatology, as aerosol scattering properties depend on the aerosol refractive index. Finally, we conclude that the major source of uncertainty is the imaginary part of the aerosol refractive index. This is critical as the atmospheric correction over land algorithm handles it with difficulty.